Surface-mounted electronic parts such as a chip capacitor and a chip inductor are usually mounted by soldering an external electrode formed in an electronic part main body, for example, to an electrode for mounting disposed on a substrate.
By the way, there is proposed, as an external electrode arranged in such an electronic part, an external electrode which has a bilayer structure having an inner layer in contact with the surface of a bare chip made of a ceramic sintered body and an outer layer laminated on the inner layer, and is formed by baking a conductive paste containing a metal powder and glass frits, and in which the metal powder in the conductive paste for forming the inner layer and the outer layer contains 80 to 95% by weight of Ag and 5 to 20% by weight of Pd, the glass frit contains 0 to 40% by weight of PbO, 35 to 65% by weight of B2O3 and 20 to 55% by weight of ZnO as main components, and the conductive paste contains the glass frit in an amount of 2 to 6% by weight with respect to the metal powder, and the inner layer and the outer layer are formed of the conductive paste of the same composition (refer to Patent Document 1).
The external electrode described in Patent Document 1 aims at improving a soldering property which is problematic in the chip type electronic part by optimizing the structure of the external electrode and the composition (metal powder, glass) of a conductive paste for forming an electrode to suppress floating of glass to the surface of the external electrode.
However, in the case of the external electrode described in Patent Document 1, there is a problem that, for example, when mounting is performed by using common Pb-free solder which contains Sn as a main component, Ag in an amount of 3% by weight, and Cu in an amount of 0.5% by weight, the electronic part falls off (i.e., the strength at a high temperature is deteriorated in a soldered portion) in the reflow repeatedly carried out multiple times after the mounting or when the chip type electronic part is used in a high-temperature environment as a car-mounted electronic part.    Patent Document 1: Japanese Patent Laid-open Publication No. 6-36969